Fuel burner



March 12-, 1935. R. M. HARDGROVE FUEL BURNER Filed Jan. 14, 1928 IN V EN TOR. 47

ATTORNEYS.

Patented Man 12, 1935 FUEL BURNER Ralph M. Hardgrove, Bethlehem, Pa., assig'nor to Fuller Lehigh Company, Fullerton, Pa.., a corporation of Delaware Application January 14, 1928, Serial No. 240,710 16 Claims. (c1. 110-104) This invention relates to a fuel burner that has I an inlet for primary air and fuel and a separate inlet or inlets for secondary air, and will be understood from the description in connection with B'the accompanying drawing in which Fig. 1 is a vertical section on the line 'I-I of Fig. 2, showing a burner constructed in accordance with the invention as viewed from outside of the furnace; and Fig. 2 is a section on the line IIII of Fig. l. The invention will be described in connection with a boiler furnace, in the walls of which water tubes are installed for keeping the walls cool, but the invention is not restricted to this particular sort of furnace. In the drawing, reference character 5 indicates the water tubes to which blocks 6 are connected to form the wall of a furnace, these blocks being preferably made up of refractory material on the side next to the furnace and metal on the other side which contacts with the water tubes. Two of the tubes are bent outwardly, as indicated at 7, to facilitate installation of the fuel burner. A conduit 8 for primary air and fuel, such as pulverized coal, gas, etc., having an elongated exit opening 9 is attached to the tubes '7.

i A casing 10 into which secondary air for combustion purposes may be introduced in any convenient way, surrounds the pipe 8 and is connected to the furnace wall so as to be air tight. Blocks 11 on opposite sides of the twotubes '7 are spaced apart in staggered relation, so as to leave staggered openings 12 on opposite sides of the pair of tubes 7 through which openings secondary air is admitted from the casing 10. The secondary air entering through the openings 12 impinges against the sides of the stream of fuel entering through the exit opening 9 and causes thorough commin gling of the fuel and air.

A fuel burner of the type above described has been known heretofore. With such burners it has been found that when they are operating at decreased loads with smaller amounts of secondary air entering through the ports or openings 12, the velocity of the air is sometimes decreased so much that satisfactory commingling of the fuel and air near the mouth of the burner is not obtained. By the present invention, the velocity of the secondary air is. maintained sufiiciently high even when decreased amounts of secondary air are being supplied.

In carrying out the invention, means are provided by whiqh the size of the ports or openings 12 for the secondary air may be decreased when the rate of supply of secondary air is decreased, thus keeping the velocity of the air sufiiciently great to cause the air to commingle with the fuel as the air impinges against the fuel stream. In the illustrative embodiment of the invention, shown in Figs. 1 and 2, two sets of vertically spaced dampers 15 at opposite sides of the fuel exit opening are mounted on vertical pivot rods 16 and are movable across corresponding air ports or openings 12 in accordance with the amount of air that is to be delivered. Each damper 15 has an arcuate inner side 17 that is moved on turning of the corresponding pivot rod 16 to vary the effective area ,of a corresponding port 12. Each damper also has a vertical concavely curved side 18 which extends beyond the arcuate-shaped side 17, as shown at 19, into the corresponding port 12.

The pair of pivot rods 16 are spaced apart within the casing 10 and have oppositely extending arms 20 and 21 respectively connected to the lower portions thereof. A connecting rod 22 provided with a turnbuckle 23 for adjusting the length thereof connects the inner free end of the arm 21 to a pivot pin 24, having an extension 25, that is adjustable in a slot 26 formed in the arm 20.

A rod 30 is pivoted to the outer end of the arm 20 and passes through the side wall of the casing 10 and through an external stop member 31 adapted to be fixed thereon by a set screw 32. A washer 33 bears against the stop member 31 and a washer 3 1 bears against a nut 35 on the outer threaded end of the rod 30. A compression spring 36 is interposed between the washers 33 and 34 which tends to move the rod when loose toward the right, as shown in Fig. 2, to thereby move the dampers toward their closed positions. The set screw 32 is loosened whenever the air pressure in the casing 10 isused to control the extent of opening of the dampers 15.

The operation is as follows: Primary air and fuel are introduced through the conduit 8 and pass out of the exit opening 9 in a wide stream or band. The secondary air is forced into the casing 10 by any convenient means, and passes through the ports or openings 12 and impinges in vertically staggered streams against the opposite sides of the stream of fuel and primary air. When the burner is being operated at high ratings, the pressure of the large volume of secondary air that is required is sufficient to force the dampers 15 into their open positions by its passage along the concave surfaces 18, and since the volume of the air is large, the velocity of the same passing through the ports or openings 12 will be suflicient to cause thorough commingling of the air and fuel. The unbalanced pressure on the sides of the projecting damper portions 19 contacted by the air streams aids in opening the dampers and compressing the 36 in accordance with the amount of secondary air that is being supplied. When the amount of secondary air is decreased for smaller ratings, the expansion of the spring 36 causes the dampers 15 to be moved toward their closed positions, thus decreasing the size of the ports 12 with decreased amounts of secondary air, so that the velocity of the smaller amount of air entering through the smaller air openings will be suflicient to cause the secondary air and fuel to be properly commingled.

The slot in the arm 20, by means of which the outer end of the rod 22 that is connected to the arm 21 can be adjusted to different positions, makes it possible to vary the rate at which the two sets of dampers can be closed with respect to each other from uniformity of rate of opening and closure of the two to a rate at which the dampers on the left hand side would be opened and closed only a small fraction of the rate of the dampers on the right hand side.

It will be clear that the spring 36 will cause the dampers to be closed automatically in accordance with the reduction in the secondary air supply. The velocity of the air will thus be kept approximately constant regardless of the quantity of air passing through each air inlet. However, by means of the set screw 32 and adjustment of the bracket in the slot 26, the dampers can be set in any dsired fixed position for conditions of operation where the rate is constant or nearly so, at a predetermined load.

I claim: 7

1. In a fuel burner, a fuel supply conduit having an elongated discharge opening at the end thereof, an air supply chamber provided with outlets arranged in staggered relation on opposite sides of said opening so as to direct air into the path of discharge from said opening, and means for varying the size of each of said outlets in response to variations in pressure in said chamher.

2. In a fuel burner, a fuel supply conduit having an elongated discharge opening at the end thereof, an air supply chamber provided with outlets adjacent the opening in said fuel supply conduit, the outlets in said air supply chamber being arranged to supply air at an angle to the fuel being discharged from said fuel supply conduit, in combination with means for varying the size of each of the outlets in response to variations in pressure in said chamber;

3. In a fuel burner, a fuel supply conduit having an elongated discharge opening at the end thereof, an air supply chamber provided with outlets adjacent the opening in said fuel supply conduit, the outlets in said air supply chamber being arranged to supply air at an angle to the fuel being discharged from said fuel supply conduit, in combination with means for varying the size of each of the outlets in response to variations in pressure in said chamber, said means being arranged to concentrate said air supply next to the fuel stream.

4. In a fuel burner, a fuel supply conduit having an elongated discharge opening at the end thereof, an air supply chamber provided with outlets arranged in staggered relation on opposite sides of the opening in the end of said fuel supply conduit so as to direct air into the path of discharge from the opening, and damper means coacting with the outlets from said air tending to produce a flame elongated transversely of the direction of fuel discharge, a plurality of staggered air inlet ports at opposite sides of said fuel burner, means for supplying air for combustion to the furnace through said air inlet ports in a plurality of high velocity jets directed towards said fuel stream and deflecting portions thereof in opposite directions at points adjacent the point of fuel discharge, and means for varying the effective flow area of said inlet ports without increasing the distance of the point of initial impingement of said air jets on said fuel stream from the point of fuel discharge.

6. A method of burning fuel in on in a furnace which comprises discharging the fuel into the furnace in a fuel stream tending to produce a flame elongated transversely of the direction of fuel discharge, supplying .air for combustion to the furnace in a plurality of staggered high velocity jets directed towards opposite sides of the fuel stream and deflecting different port-ions thereof in different directions at points adjacent the point of fuel discharge, and controlling the velocity of the air jets at their points of discharge without increasing the distance of the point of initial impingement thereof on the fuel stream from the point of fuel discharge.

7. In combination, a furnace having a fuel burner port formed in a wall thereof, a fuel bumer having nozzle means for discharging fuel through said port distributed in a stream elongated transversely of the direction-of fuel discharge, a plurality of air inlet ports spaced along one side of said fuel burner and arranged in the direction of fuel stream elongation, each of said airinletportsbeingarrangedsoastodirectair into the path of discharge from said nomle means, means for supplying air for combustion to the furnace through said air inlet ports in a plurality of highvelocity jets impinging on said fuel stream and deflecting portions thereof at points adjacent the point of fuel discharge, and means for varying the effective flow area of said air inlet ports without increasing the distance of the point of initial impingement of said'air jets on said fuel stream from the point of fuel discharge.

8. A method of burning fuel in suspension in a furnace which comprises discharging fuel-into the furnace in a fuel stream tending to produce a flame elongated transversely of the direction of fuel discharge, supplying air for combustion to the furnace in a plurality of high velocity jets impinging on said fuel stream and deflecting different portions thereof at points substantially similarly spaced from and adjacent to the point of fuel discharge, and controlling the velocity of the air jets at their points of discharge without increasing the distance of the point of initial impingement thereof on the fuel stream from the point of fuel discharge.

9. In combination, a furnace having a fuel burner port formed in a wall thereof, a fuel burner having nozzle means for discharging fuel through said port distributed in a stream elongated transversely of the direction of fuel discharge, a plurality of staggered air inlet ports at opposite sides of said fuel burner nomle'means, each of said air inlet ports being arranged so as to direct air into the path'of discharge from said nozzle means, means for supplying air for combustion to the furnace through said air inlet ports in a plurality of jets impinging on said fuel stream and deflecting different portions thereof in opposite directions at points similarly spaced from and adjacent to the point of fuel discharge, and a damper in each of said air inlet ports for controlling the discharge of air therethrough.

10. In combination, a furnace having a fuel burner port formed in a wall thereof, a fuel burner having nozzle means for discharging fuel through said port distributed in a stream elongated transversely of the direction of fuel discharge, a plurality of air inlet ports at opposite sides of said fuel burner nozzle means and arranged in the direction of flame elongation, each of said air inlet ports being arranged so as to direct air into the path of discharge from said nozzle means, means for supplying air for combustion.

to the furnace through said air inlet ports in a plurality of jets impinging on said fuel stream adjacent the point of fuel discharge, a damper in each of said air inlet ports for controlling the discharge of air therethrough, and means for controlling the dampers at each side of said fuel burner nozzle means as a unit.

11. In combination, a furnace wall having a series of spaced vertically extending cooling fluid tubes at its furnace side, a fuel burner port formed in said wall, a fuel burner having nozzle means for discharging fuel through said port and between adjacent tubes in a stream elongated transversely'of the direction of fuel discharge, a plurality of air inlet ports at opposite sides of said fuel burner nozzle means and between adjacent tubes, each of said air inlet ports being arranged so as to direct air into the path of discharge from said nozzle means, means for supplying air for combustion to the furnace through said air inlet ports in a plurality of jets impinging on said fuel stream at points adjacent the point of fuel discharge, anda damper in each of said air inlet ports for controlling the discharge of air therethrough.

12. In combination, a furnace wall having a series of spaced vertically extending cooling fluid jacent tubes, each ofsaid air inlet ports being.

arranged so as to direct air into the path of discharge from said nozzle means, means for supplying air for combustion to the furnace through said air inlet ports in a plurality of jets impinging on said fuel stream at-points adjacent the point of fuel discharge, dampers at said air inlet ports for controlling the discharge of the air therethrough, and means for controlling a plurality of said dampers as a unit.

13. In combination, a furnace wall having a series of spaced vertically extending cooling fluid tubes at its furnace side, a fuel burner port formed in said wall, a fuel burner having nozzle means for discharging fuel through said port and between adjacent tubes in a stream elongated transversely of the direction of fuel discharge, a plurality of staggered air inlet ports at opposite sides of said fuel burner nozzle means and between adjacent tubes, each of said air inlet ports being arranged so as to direct air into the path of discharge from said nozzle means, means for supplying air for combustion to the furnace through said air inlet ports in a plurality of jets impinging on said fuel stream and deflecting adduce a flame elongated transversely of the direction of fuel discharge, an air inlet port adjacent said fuel burner, means for supplying air for combustion to the furnace through said air inlet port in a high velocity jet directed toward and impinging on said fuel stream at a point adjacent the point of fuel discharge, and means for controlling the velocity of air discharge through said air inlet port without increasing the distance of the point of initial impingement of said air jet on said fuel stream from the point of fuel discharge comprising a damper positioned in the discharge end of said inlet port and movable therein to first open said inlet port on its side adjacent said fuel burner.

15. In combination, a furnace having a fuel burner port formed in a wall thereof, a fuel burner having nozzle means arranged to discharge fuel through said port in a stream tending to produce a flame elongated transversely of the direction of fuel discharge, an air inlet port adjacent said fuel burner, means for supplying air for combustion to the furnace through said air inlet port in a high velocity jet directed towards and impinging on said fuel stream at a point adjacent the point of fuel discharge, and means for controlling the velocity of air discharge through said air inlet port without increasing the distance of the point of initial impingement of said air jet on said fuel stream from the point of fuel discharge comprising a pivoted damper positioned in the discharge end of said air inlet port and having a curved air. directing surfacemovable therein to first open said air inlet port on its side adjacent said fuel burner.

16. The method of maintaining short flame combustion of a fuel to beburned in suspension in a combustion chamber into-which the fuel and velocity streams through a wall thereof, which comprises discharging the fuel into the combustion chamber in a substantially fiat transversely elongatedbtream, and separately discharging the combustion air into the combustion chamber in a relatively narrow high velocity jet at an acute angle to the plane of discharge of said transversely elongated fuel stream into the combustion chamber and at a point alongside and closely adjacent to the plane of discharge of said trans versely elongated fuel stream and impinging said air jet on and deflecting an intermediate portion of said transversely elongated fuel stream away from adjacent portions thereof adjacent its point of discharge into the combustion chamber, and controlling the velocity of the air at its point of discharge without increasing the distance of the point of initial impingement of said air jet on said transversely elongated fuel stream from the point of fuel discharge.

RALPH M. HARDGROVE. 

